Optimization Analysis of Suki Kinari Underground Powerhouse Caverns Based on an Efficient CATIA-Abaqus Model

Abstract

Underground powerhouse caverns, which are large-scale, complex-type, and intersecting circuits, are considered as a complicated, constrained, and irreversible nonlinear system. They are divided into several layers for excavation. Various stress states occur whenever they are subjected to excavation; therefore, deformation and failure arise because of stress redistribution and concentration. Based on the determinate excavation scheme, the sectional shape of underground powerhouse caverns, especially the aspect ratio of the main powerhouse, is the key factor that affects the stability of the surrounding rock masses. Furthermore, during the excavation process, the integrity and stability of rock pillar, whose thickness is determined by the interval of caverns, are considered as crucial issues, because damage occurs in the thinner rock pillar. Consequently, the interval of caverns is the important parameter that needs to be investigated. In this study, we combine building information modeling with numerical analysis to investigate the effect of the aspect ratio of the main powerhouse and the interval between the main powerhouse and the main transform chamber. For the Suki Kinari (SK) underground powerhouse caverns, the 3D terrain and geological model was created in accordance with the detailed geological information. The parameterized underground powerhouse model and the supporting system were designed by CATIA, and the numerical model that involves the excavation scheme was generated by ABAQUS. The results show the following: (1) As the aspect ratio increases, the deformation of the main powerhouse exhibits various features, indicating that the arch crown settlement reduces while the deformation of the sidewalls increases. (2) As the aspect ratio increases, the overall deformation of the particular parts exhibits the characteristic of rapidly decreasing and then gradually forming a convergent trend. (3) Intense disturbance occurs on the rock pillar because of bidirectional unloading during the excavation process, and the rock pillar weakens rapidly and then gradually stabilizes as the thickness increases, suggesting the property of exponential function of the total deformation. Finally, the conclusions are applied on the SK underground powerhouse caverns to reveal the optimal aspect ratio and interval.